PERSISTENSI MEMORI SPASIAL DAN KADAR ESTROGEN JARINGAN HIPPOCAMPUS TIKUS SPRAGUE DAWLEY YANG DIOVARIEKTOMI MENINGKAT DENGAN LATIHAN FISIK TERATUR DAN TERUKUR

Siti Kaidah, Prof. dr. Sri Kadarsih Soejono, M.Sc., Ph.D.

2012 | Tesis | S2 Ilmu Kedokteran Dasar dan Biomedis

Latar Belakang. Penurunan kadar estrogen menyebabkan gangguan fungsi hippocampus termasuk pembelajaran dan memori spasial. Penelitian-penelitian terdahulu membuktikan bahwa latihan fisik bisa memperbaiki fungsi memori pada hewan yang diovariektomi. Latihan fisik dihubungkan dengan peningkatan aromatisasi ekstragonadal, dan sintesa neurotrophin, serta mempengaruhi ekspresi reseptor estrogen. Penelitian ini bertujuan mengkaji mekanisme perbaikan memori pada tikus ovariektomi yang diberi latihan fisik dengan mengukur kadar estrogen jaringan hippocampus dan kadar reseptor estrogen-β (REβ) hippocampus. Metode. Penelitian menggunakan 10 ekor tikus Sprague Dawley betina usia 3 bulan yang diovariektomi. Satu kelompok (5 tikus) diberi latihan fisik teratur dan terukur. Tikus berlari di atas treadmill dengan kecepatan 18m/menit, kemiringan 5%, durasi 60 menit/kali/hari, dan frekuensi 5 kali per minggu, selama 12 minggu. Kelompok lainnya tidak diberikan latihan fisik. Memori spasial diukur menggunakan Morris water maze pada 2 fase yaitu fase penyelamatan diri dan fase persistensi memori. Setelah program latihan fisik selesai, diukur kadar estrogen jaringan hippocampus dan kadar REβ hippocampus. Hasil. Didapatkan perbedaan bermakna rerata kadar estrogen jaringan hippocampus kelompok tikus yang mendapat latihan fisik teratur dan terukur (33,794 ± 4,760 pg/ml/100 mg jaringan) dengan kadar estrogen jaringan hippocampus kelompok tikus yang tidak mendapat latihan fisik (20,552 ± 2,057 pg/ml/100 mg jaringan). Kadar REβ hippocampus kelompok tikus yang mendapat latihan fisik teratur dan terukur lebih tinggi (0,0278 ± 0,0015 ng/ml/50 mg jaringan) daripada kadar estrogen pada kelompok tikus yang tidak mendapat latihan fisik (0,0196 ± 0,0033 ng/ml/50 mg jaringan), tetapi perbedaan ini tidak bermakna. Tidak ada perbedaan dalam proses pembelajaran spasial antara kelompok yang mendapat latihan fisik dengan kelompok tanpa latihan fisik. Waktu latensi dan panjang lintasan kelompok tikus latihan fisik pada uji persistensi memori lebih pendek daripada kelompok tikus tanpa latihan fisik. Kesimpulan. Persistensi memori spasial dan kadar estrogen jaringan hippocampus tikus yang diovariektomi meningkat pada kelompok yang mendapat latihan fisik teratur dan terukur.

Background. The decrease of estrogen levels leads to dysfunction of hippocampus, including spatial learning and memory. Previous studies have shown that physical exercise improved spatial memory in ovariectomized rats. Physical exercise was observed to be associated with increased extragonadal aromatization and neurotrophin synthesis which in turn affect estrogen receptors expression. This study aims at examining the effect of regular exercise on levels of estrogen and estrogen receptor β (ERβ) in hippocampus and spatial memory of ovariectomized Sprague Dawley rats. Method. The present study used 10 ovariectomized Sprague Dawley rats aged 3 months old. The rats were randomly assigned into two groups, i.e. exercise group (n=5), and control group (n=5). The protocol of regular physical exercise referred that of Hao et al., (2010). During the exercise period the rats were required to keep running constantly on the treadmill at a speed of 18 m/min and at the slope of 5 %for a total duration of 60 minutes per day. The exercise was performed 5 times per week, for 12 weeks. The control group was not performed physical exercise. Spatial memory was measured using the Morris water maze. After the exercise program was completed, the hippocampus was extracted from rat brain to determine estrogen and estrogen receptors β concentration. Results. The present study revealed significant differences in the mean levels of estrogen hippocampus between exercise group (33.794 ± 4.760 pg / ml/100mg tissue weight) and control group (20.552 ± 2.057 pg / ml/100 mg tissue weight). There was no significant difference in ERβ hippocampus levels between exercise group (0.0278 ± 0.0015 ng / ml/50 mg tissue weight) and control group (0.0196 ± 0.0033 ng / ml/50 mg tissue weight). In the Morris water maze tests, there was no difference in the spatial learning between both groups. The spatial memory retention of exercise group was significantly better than control group. Conclusion. Spatial memory retention and hippocampal estrogen levels of ovariectomized rats increased in the group which performed regular physical exercise.

Kata Kunci : latihan fisik, memori spasial, hippocampus, estrogen, REβ